This invention relates to apparatus for programming a radio transmitter or receiver and more particularly to automatic apparatus adapted to program a transceiver rapidly and reliably.
There exists many radio receivers and transmitters which are employed by the public in relatively widespread applications. As is known, a class of such transceivers operate in the frequency spectrum reserved for mobile radiotelephone facilities. Such transceivers are located directly in a vehicle and enable one to utilize telephone facilities via an automobile or other vehicle. It is desirable in such an environment to enable an untrained operator to employ the transceiver without fear that the frequency of operation will be unauthorized or in general use the transceiver under permitted operating conditions in regard to frequency, output power and so on. In order to accommodate such requirements, the prior art includes many examples of radiotelephone equipment which enable selected operation by the use of automatic control techniques.
Hence, a prior art system employs punched plastic cards which are read or scanned by a card reader. The data contained on such cards is converted into proper control voltages or levels to enable the apparatus to control the frequency, mode and output power of the radiotelephone. This system requires elaborate card storage facilities, relatively expensive card reading devices and further requires a large cable interface between the control apparatus and the radiotelephone.
Still other systems as the type shown in U.S. Pat. No. 3,581,019 entitled "Card Control to Radiotelephone" issued on May 25, 1971 to Donald P. Ryan employs a punched or embossed card which when inserted in a guide slot controls a cross bar matrix. The card, as indicated above, is decoded and the decode signals operate to control the matrix in order to provide control signals to the radiotelephone. Such systems employ a plurality of cards mounted in a rotating drum to enable multiple channel selection, while due to the mechanical nature of the device are relatively slow in effecting control.
It is therefore an object of the present invention to provide a control apparatus for a radiotelephone which is capable of controlling the channel frequency, mode of operation (transmit or receive) and power levels based on the dialing of a multiple digit number. The apparatus employs a programmable read only member (PROM) which can be erased and reprogrammed to provide channel selection. Based on the apparatus employed, the system requires a reduced number of interconnecting lines to afford remote control of the transceiver and results in a significant decrease in the per channel cost than would be available with prior art devices. Based on the format of the apparatus, the system is adaptable for expansion and hence, can accommodate with a minimum of changes, additional channels.
It is, of course, understood that while the system to be described is specifically intended for use in a radiotelephone, the techniques and apparatus to be described can be used in individual radio receivers and/or transmitters.